It is easy enough in principle, but in practice needs to be done very carefully to avoid problems at a later date.
There is an established concept, called fractional ownership, and from recollection Barnard Hamilton have put a property (or more than one) to the market on this basis. This is aimed at individuals who want (or can only afford) to have more than a timeshare week, but less than full ownership. You might well be advised to look at their model, since even going in with family / close friends you will still need a framework to deal with a number of matters.
Off the top of my head you need to consider - title issues; allocation of use; maintenance; refurbishment; onward sale.
From business experience if you double the number of people involved you square the number of potential problems!
allanglens